420 EXPERIMENT STATION RECORD. [Vol. 38 



" Of special significance for the fixation of nitrogen in water is the parasitism 

 or symbiosis between green water plants, especially algse. and short bacilli of 

 the pneumonia group. Their action is not increased by sodium nitrate or 

 artificial fertilization. In Wielenbach it was found that by nitrogen-free ferti- 

 lizer, with the help of these nitrogen-fixing bacteria, a multitudinous increase 

 of fish was produced. The action of the nitrogen-fixing bacteria shows itself 

 further in a tenfold enrichment of the ground at the bottom of the pond. The 

 significance of free living nitrogen-fixing bacteria, especially the aerobacterial 

 and radiobacterial forms, can be favorably compared with that of the nodule 

 bacilli for the legumes." 



Microorg'anisms of waste and cultivated peat soils, T. Arnd (Centbl. Bakt. 

 [etc.], 2. Abt., 45 {1916), No. S-25, pp. 554-574; abs. in Internat. Inst. Agr. 

 [Rome}, Internat. Rev. Sci. and Pract. Agr., 7 {1916), No. 12, pp. 1144, 1^45; 

 Jour. 8oc. Chem. Indus., 36 {1917), No. 15, p. 897).— Preliminary trials at the 

 Bremen Experiment Station to ascertain the effect of drainage, liming, and 

 tillage on the bacterial life of peat soils, gave the following general results: 



Ammonifying organisms were present in all samples but were far more active 

 in surface soils than in subsoils and in cultivated than in waste land. The 

 breaking up of waste land affected the bacterial life only to a depth of about 

 8 in. of soil. No nitrifying organisms were found in waste land or cultivated 

 land, except such as received a dressing of more than 0.5 ton of lime per acre. 

 More than 1 ton per acre appeared to be necessary to produce active develop- 

 ment of the nitrifying organisms in the peat itself. All the samples tested were 

 able to reduce nitrates. The surface soil of waste land was not much more 

 active than the subsoil, but the surface soil of cultivated land showed much 

 more activity, especially where tillage had been accompanied by liming. Similar 

 relations were observed in respect to the power of decomposing cellulose. As 

 with ammonification and nitrification, the maximum decomposition of cellulose 

 occurred when the soil had previously received a dressing of dung. In no 

 sample of soil was Azotobacter present. Surface soils and cultivated .soils fer- 

 mented mannitol more readily than subsoils and waste land, the maximum effect 

 again being obtained with a manured plat. 



Soil sterilization, F. O. Ockerblad, jb. {Vermont Sta. Bui. 203 {1917), pp. 

 14-16). — Studies with greenhouse soil containing approximately 3,250,000 or- 

 ganisms per cubic centimeter are briefly noted, in which steam, phenol, sul- 

 phuric acid, formaldehyde, carbon disulphid, and pyridin were employed. The 

 steaming was done in an autoclave for 1, 2, and 5 hours and for half-hour 

 intervals on three successive days, the soil being placed in glass tubes 1 in. 

 wide and 12 in. long and in 8 in. flower pots. 



The surface soil exhibited little difference for the several treatments, over 

 99 per cent of the organisms being killed, while at a depth of 30 cm. (about 

 1 ft.) wide differences occurred. The 5-hour treatment proved most effective 

 at all depths. The relatively high percentage of organisms killed at depths 

 of 20 and 30 cm. is thought to be due to the penetration of the dry heat through 

 the walls of the glass tube, and that equally good results would be obtained 

 in actual practice is deemed unlikely. The percentage of organisms killed in 

 the pots appeared to be fairly uniform throughout the soil column. Oats 

 grown in pots of steamed and unsteamed soil produced approximately one- 

 seventh more dry matter on the treated soil. 



The chemicals were used in solutions of 0.1, 0.5, and 1 per cent, except for- 

 maldehyde which was used in 0.4, 0.8, and 1.2 per cent solutions, and were 

 applied to greenhouse beds 5 in. deep, the plats being covered for one and 

 two days. Phenol and carbon disulphid were generally ineffective; pyridin 



